Lee de forest



No. 743,597. PATENTED JAN: 5, 1904.

DHFOREST. Y WIRELESS SIGNALING DEVICE.

- APPLICATION FILED 1330.24, 1902.

N0 MODEL.

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LEE DE FOREST, OF NEW Y ORK, N. Y.

WIRELESS SIGNALING DEVICE.

SPECIFICATION forming part of Letters Patent No. 748,597, dated January 5, 1904.

Application filed December 24, 1902. Serial No. 136,435. (No model.) 7

To all whom it may concern:

Be it known that 1, LEE DE FOREST, a citizen of the United States, and a resident of the city of New York, borough of Manhattan, in the county and State of New York, have invented certain new and useful Improvements in Wireless Signaling Devices, of which the following is a specification.

My invention relates to an improvement in devices for use in wireless signaling by which the radiated energy may be concentrated in the direction desired, one feature thereof involving the use of a reflector of the waves and another feature involving the use of horizontal directive and concentrating conductors.

My invention comprises the novel features and parts and combinations thereof, which will be hereinafter described, and particularly pointed out in the claims.

Figure 1 represents in perspective a reflector of a peculiar construction. Fig. 2 shows in perspective another form of apparatus involving my invention. Fig. 3 shows in plan the same form as shown in Fig. 2 except that lag or impedance coils are employed to enable the antenna being placed near the reflector. Fig. 4 shows in perspective a further modification, and Figs. 5 and 6 are respectively plan and elevation of a modified construction.

It has heretofore been proposed to use a reflector for the waves radiated from a sending-conductor or antenna, the same to consist of a series of upright conductors which are disposed about the radiating-antenna in a curved line, more or less corresponding with a segment of a circle. So far as I am aware the conductors forming such a reflector have been insulated or not grounded.

In accordance with my present invention I surround the radiating-antenna A with a series of vertical conductors a, which may be called secondary antennae, said conductors being disposed about the antenna A in a curve, which theoretically should be a parabola having its focus in the antenna A. This theoretical construction may, however, be departed from by means hereinafter explained.

The conductors forming the reflector are, however, each grounded, either as in Fig. l by a direct ground connection E or, as is shown in the other figures, by a conductor B, which extends horizontally in the direction it is desired to transmit the signals and is there connected with a ground E through a secondary spark gap or gaps S. A sparkgap S is placed at the base of the antenna A, which may be charged by any suitable apparatus, a coil G, battery H, and key I being herein shown for this purpose.

In the form of my device shown in Figs. 2 and 3 the vertical conductorsh, forming the reflector, each have their base connected with the antennaA bya conductor D' and are also each connected with a conductor B, extending horizontally in the direction it is desired to transmit the signal. These horizontal conductors are each grounded at their outer ends through a secondary spark gap S. This ground connection should be removed from the antennaa distance corresponding toa multiple of a quarter-wave length, preferably a half-wave length The secondary radiatingantennee a, forming the reflector, should preferably be located at such a distance from the main or primary antenna A that the waves radiated therefrom and traveling in the direction of the conductors B will be in stepor phase with that part of the wave radiating from the primary antenna A, which is traveling in the same direction. To secure this, the length of the conductors connecting each of the reflecting or secondary antennae a with the main antenna A added to the length of the conductors B,conneoted thereto, should be equal to a half-wave length more than the length of the conductor B, which is connected stances be undesirable to separate the primary and secondary antennae to such a distance, the same result is obtained by interposing lag producing or retarding devices in the conductors D, connecting the bases of antenna A and reflectors asuch, for instance, as the inductance-coils 0. (Shown in Figs. 3 and 4..) The actual length of the conductors B may also be reduced by inserting therein impewith the antenna A. As it would in most indance-coils or other lag-producing devices after the manner usual when such a result is desired.

In Fig. 4 a modification is shown in which the conductors B are replaced by a sheet of conducting material covering substantially the same area as the conductors B.

Fig. 5 shows in plan, and Fig. 6 in elevation, a construction which in the main is like that shown in Figs. 2 and 3. One structural difficulty attendant upon the use of the reflectingconductors is that their supports present so much surface to the wind and in such an unsupported form that they are liable to be blown down. To remedy this, I'prefer to continue the supporting structure until its ends meet, thus forming a complete inclosure, which would most naturally be of a circular shape or approximating thereto. This structure except for the reflecting-conductors or secondary antennae should be of such material as will not seriously interfere with the free passage of the electric wavessuch, for instance, as wood. Such a structure is shown at F in Figs. 5 and 6. I thus complete the curved form of the reflector and strengthen it, so as to enable it to better resist the windpressure and in addition do away with the exposed concave side which catches the wind. Being of wood it offers no obstacle to the passage of the waves. The horizontal conductors B or B, extending outward from the base of the antennae, cooperate with the antenna A and the reflector-conductors or secondary antennae a to give a directional efiect to the waves, whereby a much larger percentage than usual of the electrical energy is directed along the plane of said conductors and being once directed along this plane continues in that direction. I am thereby enabled to secure a greater range and effect with a given power.

The above feature is in addition to the reflection caused by the conductors a and would occur if the conductors a were omitted. This action is fully set forth and generically claimed in a divisional application for patent filed by me December 8, 1902, Serial No. 134,312, and is not, therefore, herein broadly or separately claimed.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, is-

1. In wireless signaling, the combination with an antenna and means for communicating electric oscillations thereto, of a reflector for said oscillations and a ground connection therefor containing a horizontal conductor ex tending in the direction in which the waves are reflected.

p 2. In wireless signaling, the combination with an antenna and means for communicating electric oscillations thereto, of a reflector for said oscillations and a ground connection therefor containing a horizontal conductor extending a half-wave length beyond the antenna in the direction in which the waves are reflected.

3. In wireless signaling, the combination with an antenna and means for communicating electric oscillations thereto, of a reflector comprising vertical conductors which are connected with the base of the antenna and a conductor connected with the base of each of said reflector-conductors and extending in the direction in which the waves are reflected and a ground connection therefor located a half-wave length beyond the antenna.

4. In wireless signaling, the combination with an antenna and means for communicating electric oscillations thereto, of a series of vertical conductors forming secondary antennae disposed about one side of the primary antenna to form a reflector, a conductor connecting each conductor of the reflector with the primary antenna, a horizontal conductor extending from the base of each secondary antenna in the direction in which the waves are reflected, a ground connection for said horizontal conductors located at a multiple of a quarter-wave length from the primary antenna, the length of the connection between the base of the primary antenna and points in the horizontal conductors abreast of the primary antenna being equivalent to a half-wave length.

5. In wireless signaling, the combination with a radiating-conductor and means for communicating electric oscillations thereto of a reflector for said waves connected with the said wave-radiating conductor, said connections containing lag-producing devices adapted to cause the reflected waves to coincide in phase with the waves directly radiated from the radiating-conductor and traveling in the same direction.

In testimony whereof I have hereunto affixed my signature, this 17th day of December, 1902, in the presence of two Witnesses.

LEE DE FOREST. 

